[ntp:questions] ntpd + TrueTime GPS + daylight saving

Richard B. Gilbert rgilbert88 at comcast.net
Thu May 24 14:06:40 UTC 2007

Ralf Gross wrote:
> Hi,
> I'm running a local ntpd server (CentOS 4.3) with an attached TrueTime
> NTS 100 GPS device.
> The /etc/sysconfig/clock contains
> ZONE="Europe/Berlin"
> UTC=true
> ARC=false
> The NTS 100 is set to
> F66 OFF
> F01 +00:00
> F03  UTC  05/24/07 07:31:19
> (Daylight saving is off.  Timezone is +00:00)
> This is working fine for 2 years now.  Today I was asked, if the daylight
> saving information is transmitted too.  There seems to be some devices
> that have no information about daylight saving .
> <quote>
> The xxxxx is configured in order to be updated once a day from the NTP
> server (Network time protocol).
> If the server is also updated according to winter/ summer's clock, then
> automatically the xxxxx will be synchronized for the different
> seasons.
> </quote>
> Am I right that our local ntpd sends the ntp packages in UTC?
> Ralf

You are right.  NTP and the NTP daemon do not deal with time zones at 
all .  UTC is the ONLY time that NTP deals with.  UTC is not affected by 
human notions about "daylight time" or "standard time".

Time zones, when dealt with at all, are handled by the operating system.
You tell the O/S what time zone you want it to use when displaying the 
time and it takes care of adding or subtracting the offset to get 
"local" time, whatever that means.

Many operating systems allow the users to set the time zone for their 
own process so that a system in Chicago can accommodate users in Tokyo, 
New York, and Los Angeles.

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